Dental calculus, or tartar as it is sometimes called, is a deposit which forms on the surfaces of the teeth at the gingival margin. Supragingival calculus appears principally in the areas near the orifices of the salivary ducts; e.g., on the lingual surfaces of the lower anterior teeth and on the buccal surfaces of the upper first and second molars, and on the distal surfaces of the posterior molars.
Mature calculus consists of an inorganic portion which is largely calcium phosphate arranged in a hydroxyapatite crystal lattice structure similar to bone, enamel, and dentine. An organic portion is also present and consists of desquamated epithelial cells, leukocytes, salivary sediment, food debris, and various types of microorganisms.
As the mature calculus develops, it becomes visibly white or yellowish in color unless stained or discolored by some extraneous agent. This is undesirable from an aesthetic standpoint.
Mechanical removal of calculus periodically by the dentist is routine dental office procedure. A variety of chemical and biological agents have also been suggested to retard calculus formation or to remove calculus after it is formed. Pyrophosphate salts are chemical agents known to have the ability to retard calculus formation as described, for example, in U.S. Pat. No. 4,999,184, to Parran, Jr. et al., issued Mar. 12, 1991, the disclosure of which is incorporated herein by reference in its entirety.
In addition to the pyrophosphate salts, other polyphosphates are also know to help retard calculus formation. U.S. Pat. No. 4,627,977, issued Dec. 9, 1986, to Gaffar et al. discloses the use of linear molecularly dehydrated polyphosphate salt in combination with two additional ingredients which inhibit enzymatic hydrolysis of the polyphosphate. U.S. Pat. No. 4,247,526, to Jarvis et al., issued Jan. 27, 1981, discloses the use of a pharmaceutically acceptable condensed phosphate salt in addition to dicalcium phosphate dihydrate and trimagnesium phosphate. The glassy polyphosphates are also known to react with ionic fluoride, but only at extreme temperatures (800.degree. C.-900.degree. C.). Although polyphosphate containing oral care products are known, there is a continuing need to develop improved products.
The present inventors have discovered that certain polyphosphates, in particular, linear polyphosphates with average chain lengths greater than 4 will significantly react with ionic fluoride in oral compositions at ambient temperature and produce monofluorophosphate ions, in addition to altering the pH of the composition. This reaction compromises the ability of the oral composition to provide stable ionic fluoride and polyphosphate to the oral surfaces.
Therefore, it is an object of the present invention to provide stable oral formulations comprising two dentifrice compositions which are contained in physically separated compartments, allowing maxium fluoride and polyphosphate delivery to the oral cavity. The first dentifrice composition comprises a polyphosphate and a buffering agent while the second composition comprises a soluble fluoride ion source and a buffering agent. It is also an object of the present invention to provide a first dentifrice composition comprising a polyphosphate, an alkali metal bicarbonate salt, an alklali metal carbonate salt, calcium peroxide, and an abrasive polishing material and a second composition comprising sodium fluoride, a mixture of pyrophosphate salts, and silica. It is also an object of the present invention to provide dentifrice formulations with improved antitartar activity through the use of polyphosphates.
These and other objects of the present invention will become readily apparent from the detailed description which follows.
All percentages and ratios used herein are by weight of the specific dentifrice composition and not of the overall oral formulation that is delivered, unless otherwise specified. All measurements are made at 25.degree. C., unless otherwise specified.